Fifty five years had passed before
the next eruption occurred in 1925. A series of minor seismic
events on July 28th warned the inhabitants of Santorini that
the volcano was waking. A group of geologists sent by the
Greek government, as well as German and Dutch volcanologists
went to observe.

The eruption, which began on August 11th, was heralded by
tremendous fountains of steam and water in the area of Kokkina
Nera (where the Hot Springs are). Volcanic activity included
marked increase in temperature in the bay of the Kokkina Nera,
the sinking of Nea Kameni's east coast and the formation of
the Daphne dome (named after the first war ship to arrive
on the scene immediately after the eruption).

Explosions sent a phreatomagmatic eruption column (volcanic
ash) 3,3 kilometers into the sky. Lava fragments rained over
an area with a radius of more than 850 meters. An estimated
100 million square cubic meters of lava flowed in two broad
branches, one to each side of Mikra Kameni, filling the channel
separating it from Nea Kameni and adding substantially to
the land surface of the island which had now become a single
mass.

A few days later the center of volcanic activity moved 200
meters to the southwest to a site which today has several
craters grouped together. These craters and the pyroclastic
cones of lava fragments which made them were created by the
volcanic activity of 1925.

The first wave of activity ceased in January 1926 for four
months, only to start up again for a brief period. From May
1926 until January 1928 there was a pause, which was followed
by four explosions followed by another explosion that created
the Nautilus Dome. This dome is no longer visible for it was
covered by lava produced during the next stage of activity.

The Eruptions of 1939-1941

A series of explosive phases and
upheaval of land mass characterize this period. After a period
of quiescence of only 11 years, the volcano awoke once again.
Early in May 1939, it was observed that the waters in the
little bay of Agios Georgios with its chapel, were heating
up, and the coastline was subsiding. A submarine explosion
at the harbour entrance on August 20th cleared the vent for
the new magma which began to appear, creating a small dome
which the volcanologists of the time baptized 'Triton'.

One month later, the focus of volcanic activity shifted a
few hundred meters to the northeast where it created lava
flows and a dome which were given the name of 'Ktenas' after
Greek geologist who studied the Kameni eruptions.

This lava filled the little harbour of Agios Georgios and
covered the Triton dome. Between November 1939 and July 1940,
the volcanic activity shifted even farther to the northeast,
creating the Fouque lava flows and dome, named after the French
naturalist who studied Santorini and the eruptions of Kameni
up until 1866.

In July 1940 two new centers of activity appeared to the
south of the Fouque center. The first was called Smith, after
an American and the second Reck, after a German volcanologist,
both of whom had studied the 1925 eruptions. These centers
produced lava domes and flows which covered the western slopes
of the now single island of Nea Kameni and flowed into the
sea. The explosive activity of this period was not severe,
and the height to which volcanic ash was ejected did not exceed
1,200 meters.

Late in August 1940, two major explosions from the summit
of the island blew the old rock plug from 1866 into the air,
opening two large craters each 50 meters across. These are
the craters which visitors to the island go to see today.
There was no magma outflow from these craters. Towards the
end of November of that same year, viscous lava began to flow
from a vent a bare 100 meters to the east, creating the lava
fields named 'Niki' (Victory), in honour of the Greek victories
in Albania. The lava covered the eastern slopes of the island,
stopping just short of the sea.

This eruptive cycle came to an end in July 1941.

The Eruption of 1950

The most recent volcanic eruption
in Greece was that which shook Santorini early in January, 1950.
There had been advance warning in the form of seismic events
since the previous August. On January 10, 1950, an explosion
blew the acid rock plug to the southern foot of the Niki dome,
opening a vent for the new magma which began to pour out. This
was punctuated by intense explosive activity which spewed tephra
1000 meters into the air, and dropped lava fragments within
a range of 850 meters all around.

The phreatic explosions and lava flow continued until February
2nd, creating the youngest volcanic rocks in Greece and was
named the 'Liatsikas Dome' after the Greek geologist. The
Reck dome disappeared, leaving a huge funnel-shaped depression.

Victor Akylas describes one
of the 1925 eruptions in his book entitled 'The Volcanoes
and the Island of Thira':

"Nothing can compare with
the superb eruption of August 19th, when at about 3 o'clock
in the afternoon there was a tremendous roar; a huge cloud
of steam darkened the whole surrounding area, volcanic ash
spewed with terrific force several kilometers into the air,
while glowing fragments of lava rained over an area 3,000
meters in diameter all around the Daphne crater. This was
followed by heavy showers of volcanic ash".